LE10H-1 in 4345?

[Stevedel]

Having collected most drivers and horns for a pair of 4345 clones, (2245H, 2420 and HL91 horn-lens.) I found a pair of LE10H-1 10 in. in need of surrounds. I also purchased a pair of 2404H tweeters. I am mostly concerned about the differences between the LE10H and 2122. I know that the LE10 is less efficient but I will tri-amp the low, low-mid and mid-high. I'll worry about the super-high later. I think that it's worth a try. Any and all comments will greatly appreciated. Thanks.

[speakerdave]

Reading your post has made me realize how really freakin' sad it is that the 2122 cone kit has been discontinued, and it is really not possible to build that speaker anymore.

[4313B]

I think JBL has a few C8R2122 kits left but they have to be asked for specifically.

The LE10H is something like 6 dB less efficient than the 2245H and 9 dB less efficient than the 2122H. It sounds very good though once one gets past the efficiency difference.

[ivica]

I think JBL has a few C8R2122 kits left but they have to be asked for specifically.

The LE10H is something like 6 dB less efficient than the 2245H and 9 dB less efficient than the 2122H. It sounds very good though once one gets past the efficiency difference.

Hi 4313B,

From JBL T/S parameters:

2245H ....Eff= 2.1% (correspond to SPL=95.2 dB 1m,1W)
2122H ....Eff= 2.4% (correspond to SPL=95.8 dB 1m,1W)
2123H ....Eff= 3.5% (correspond to SPL=97.4 dB 1m/1W)
2202H ....Eff= 6.0% (correspond to SPL=99.4 dB 1m/1W)
LE10H ....Eff= 0.7% (correspond to SPL=90.5 dB 1m/1W)

Regards
Ivica

[4313B]

Unfortunately it doesn't work that way. One has to measure the actual efficiency over the intended bandwidth.

For example, carefully examine the bandpass for the 2122H in the 4345. Note the gain due to the narrow passband as well as the attentuation via the fixed pad and variable pad set to the reference standard.

Another example, the 2123H is considered a 101 dB transducer.

The LE10H has always been considered an 89 dB transducer.

[ivica]

Unfortunately it doesn't work that way. One has to measure the actual efficiency over the intended bandwidth.

For example, carefully examine the bandpass for the 2122H in the 4345. Note the gain due to the narrow passband as well as the attentuation via the fixed pad and variable pad set to the reference standard.

Another example, the 2123H is considered a 101 dB transducer.

The LE10H has always been considered an 89 dB transducer.

Hi 4313B,

I can absolutely agree with You, that the measurements with the real driver with the real network (if possible) is the best solution.

for 2123H look at:
http://www.audioheritage.org/vbullet...l=1#post298699

for 2122H look at:
http://www.audioheritage.org/vbullet...l=1#post110497


for LE-10H:
http://www.audioheritage.org/vbullet...l=1#post110723


But all of them were measured with 'voltage source amplifier', so there were no influence of the network impedance in the 'driving path'

Regards
Ivica

[4313B]

I provided all those plots.

The 2123H is considered a 101 dB transducer.
The 2122H is considered a 98 dB transducer.
The LE10H is considered a 89 dB transducer.

They all have a rising response in the 300 to 1200 Hz range which would most likely be mitigated with any passive or active filter used, unless an end user preferred that type of sound.

The most interesting is that the 2122H is considered a 98 dB transducer in the 4345 for bi-amp purposes. I posted the voltage drives of the 4345 years ago and they show what happens when the bi-amp switch is thrown. One would think that the 98 dB rating would only occur in passive mode (when the narrow passband adds gain). But, for whatever reason, JBL rated the ten-inch three-way in the 4345 a 98 dB subsystem for bi-amp purposes. There are numourous agents at work, the narrow passband in passive mode, the small subenclosure, the large baffle width, the actual sensitivity of the transducers within the passband.

I'm not arguing that you are wrong on paper. I'm merely pointing out that in real life it just doesn't work out that way. But the OP is going to have to work it all out himself. He will have to determine whether or not he can live with the efficiency hit, whatever it ends up being in his particular system. There will be some gain from the small enclosure, there will be some gain based on baffle width. Going active will bypass the built-in gain followed by attentuation in the stock 4345 passive network.

[Mostlydiy]

On the other hand using the 2123 instead of the 2122 will have the opposite complications? Do you have to change the x-over or is the differences in sensitivity to small to bother with? I quess it more or less only tilts the responce towards the ligher side making it a more or less a personal preferance tweek?

/Mostly

[Mannermusic]

On the other hand using the 2123 instead of the 2122 will have the opposite complications? Do you have to change the x-over or is the differences in sensitivity to small to bother with? I quess it more or less only tilts the responce towards the ligher side making it a more or less a personal preferance tweek?

/Mostly

Hi Mostly. Not the ultimate expert on all this but have done a few of these filter designs using Harris modeling software (not as sophisticated as the stuff G. uses). But, the bottom line is, all these speakers are different electrically and mechanically so require somewhat different filtering to get perfect blend. That's not to say they won't work, but, ideally they need different filters. With an active filter it's easier and the best way to find out which one you like the best. One man's experience.

[Mostlydiy]

I imagine you guys have talked about and tried lots of things to get the most out of the system. I will mention a few things that I would do if I had a pair at home for my primary system.

• Get rid of the bi-amp switch. Hardwire it in which ever mode you want it. The switch is not that great.
• If you can work out bi-amping do so. The difference in the 2245H and 2122H will be amazing. The crossover will have to be non standard. Neither driver is flat around crossover so the voltage drives will need to be adjusted to get proper acoustic bandpasses.
• The network components should be updated and this isn't easy. All the capacitors should be polypropylene and you would want to use air core inductors where ever possible. I believe the 4345 used some tapped iron cores. Those are hard to replace with aircores because the surrounding network topology would have to change and all of the values have to be re-engineered. I would suggest leaving them alone unless you are really good at this stuff.
• If you can swing it, go to a biased network. The difference is unbelievable.
• The ring radiator hates passive networks. A major improvement in the upper range would be to drive the 2405 from its own little amp. You only need 3 or 4 v rms. The 2405 does 110 dB for 2.83v. It is padded way down in the system. There is little real power at those frequencies anyway. You only need to know the voltage output of the amp, power is irrelevant. The 2405 is about 12 ohms and won't draw much current. I would use some little chip amp with a 2ond or 3rd order low level highpass in front of it. Take off the passive network to the ring and just feed it straight. Make sure the amp doesn't make a DC thump on turn on or turn off. That will fatigue the diaphragm. The amp will also have to have really low noise characteristics as any hiss will be really loud directly into the ring. I used to use an old Marantz 1030 integrated amp to run my rings. I could separate out the power amp section and the tweeters always sounded really good.
• The L-pads aren't so hot either, particularly after all of these years. Once you have your preferred balance, it is fairly easy to measure each leg of the L-pad and replace it with fixed resistors.
• I notice from many of the pictures that the system is elevated on blocks. It is very good to get the 2245 up off of the floor to minimize midbass fatness.

For resale reasons, you should be very careful about doing as much of this as possible reversibly.

Thank you Manner,

Maybe the best way to improve the 4345 is checking this list provided by the one that actually designed the speaker rather than start changing drivers.

/Mostly

[4313B]

Or simply go with the M2 solution (which isn't simple at all in practice) and go active with DSP

[Mannermusic]

Thank you Manner,

Maybe the best way to improve the 4345 is checking this list provided by the one that actually designed the speaker rather than start changing drivers.

/Mostly

Couldn't go wrong on that! That may be the best post on this site. I'm waiting for one of the EEs here to draw us a little schematic for the UHF chip amp upgrade. I agree with GT, having the UHF on its' own amp is one of the best improvements possible for these 3 and 4 way rigs. I may give it a try and see if I can blow a fuse or two! Know just enough to be dangerous.

[Mannermusic]

Or simply go with the M2 solution (which isn't simple at all in practice) and go active with DSP

Yeah, that stuff is getting beyond us old 030 guys. Hey, it's just for home hi fi, doode!

[Stevedel]

Thanks ivica, for the reference to the section, on the site, that includes the bare driver response curves. It will be most helpful. Regards, Stevedel.

[Stevedel]

Thanks, 4313B, for supplying those plots. Stevedel